Multi-Layer Flat Rupture Disc
Product Model: ZD-FL12 (Multi-Layer Safety Disc)
Construction: Two or more independent flat metal membranes stacked in a single holder, with an intermediate pressure monitoring port.
Key Feature: Leak-Before-Burst (LBB) safety. If the primary (process-side) disc develops a pinhole leak, pressure builds in the interspace, triggering an alarm without a full rupture.
Pressure Range: 5 barg to 40 barg.
Primary Use: Protection of systems containing highly toxic, pyrophoric, or extremely valuable media where any uncontrolled release is unacceptable (e.g., semiconductor CVD gases, certain pharmaceutical intermediates, poisonous chemicals).
Overview
For the most hazardous processes, a standard single membrane rupture disc represents a single point of failure with immediate, catastrophic consequences if it leaks or bursts. The multi-layer safety disc introduces an intermediate, monitored safety layer. It consists of a primary disc exposed to the process and a secondary disc, with a sealed interspace between them. This design provides an early warning system: a leak in the primary disc pressurizes the interspace, which can be detected by a pressure switch or gauge, allowing for a controlled shutdown before the secondary disc fails and the contents are released. This adds a critical layer of safety and operational intelligence.
Features & Benefits
Leak Detection Capability: Provides warning of primary disc degradation or incipient failure, enabling preventive action.
Redundancy: Two independent barriers must fail for a release to occur, significantly increasing system safety integrity.
Process Protection: For valuable or air-sensitive materials, it prevents exposure to atmosphere from a tiny pinhole leak in the primary disc.
Regulatory Compliance: Meets the stringent safety layer requirements for high-hazard processes in many industries.
How It Works
Under normal operation, the primary disc seals the process. The interspace is at a reference pressure (often atmospheric or slightly pressurized with an inert gas). If the primary disc corrodes or fatigues, creating a micro-leak, process fluid enters the interspace, raising its pressure. This pressure rise is detected by an instrument. If the leak progresses and the primary disc fully fails, the secondary disc acts as a backup, rupturing at its (usually higher) set pressure to provide ultimate overpressure relief.
Specifications (Descriptive)
Typically used in smaller, critical lines: DN25 to DN80. Primary disc burst pressure is set for process protection. Secondary disc burst pressure is set higher, as a backup. The assembly includes a 1/4" NPT or similar connection port on the holder for monitoring the interspace pressure. Materials for both discs are chosen based on the process, often exotic alloys. A pressure switch, gauge, or transmitter must be separately specified for the monitoring port.
Q&A
Q: What happens after a leak is detected in the primary disc?
A: The process should be safely shut down immediately. The entire multi-layer disc assembly must be replaced, as the primary disc is compromised. The secondary disc remains intact but should not be relied upon as the sole primary barrier after such an event.
Q: Is the burst pressure of the assembly the primary or secondary setting?
A: For overpressure relief, it is the secondary disc's setting that determines when full rupture occurs. The primary disc's lower (or same) setting is for leak detection and first-stage relief.
Q: How is the interspace monitored?
A: It is typically connected to a pressure switch set to alarm at a low pressure (e.g., 0.5 barg), or to a transmitter for continuous monitoring. The connection must be kept sealed and protected.
About ZD Safety
We provide safety solutions for when failure is not an option. Our multi-layer discs represent a proactive, engineered safety approach, moving from passive containment to active monitoring and redundant protection for the world's most sensitive processes.
